So I've realized that, despite the fact that I've only had one relationship with a guy, which ended with him leaving me, I'm tired of relationships.

Hun, I had 4 relationships. 3 of which ended with me getting hurt (1. decided without me that he was going to be an open relationship and flirt with others/stopped loving me. 2. was used. 3. cheated on for 4 months) and I'm not even tired of relationships.

Yeah I may have a hard time trusting someone now but I still try. You shouldn't give up after your first and only one.